TWI467913B - Ac motor driving device - Google Patents

Description

AC motor drive

The present invention relates to an AC motor driving device, which is an AC motor driving device that supplies DC power from a DC power source into AC power by a inverter, and is particularly useful for controlling the DC. An AC motor drive device for an electric power storage device.

In the AC motor drive device, a large current flows in order to accelerate the AC motor, and a regenerative current is generated during deceleration. This kind of regenerative current is released as heat by the resistor alone, and is unfavorable for energy utilization.

Therefore, a power storage device connected in parallel with the inverter has been interposed between a converter for direct current conversion and an inverter for alternating current. The power storage device includes a power storage element such as a large-capacity electrolytic capacitor or an electric double-layer capacitor, and a DC/DC converter provided between the power storage element and a DC bus of the DC converter. And a control circuit for controlling the DC/DC converter to charge and discharge between the DC bus and the power storage element.

For example, in the AC motor drive device equipped with the power storage device, the power stored in the power storage element is discharged to the DC bus by the DC/DC converter during operation of the motor, as described in Patent Documents 1, 2, and 3, for example. And supplying the electric power to the alternating current motor by converting the electric power into alternating current power by a reflux. On the other hand, when the motor is regenerated, since the regenerative power is passed through the inverter The voltage of the DC bus rises, so the bus voltage is charged and stored in the power storage element by the DC/DC converter. Thereafter, the electric power stored in the power storage element is discharged to the DC bus by the DC/DC converter, and power regeneration is performed. Thereby, in the AC motor drive device equipped with the power storage device, the motor drive current can be averaged, and the regenerative electric power can be utilized effectively.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-103769.

Patent Document 2: Japanese Laid-Open Patent Publication No. 2001-320893.

Patent Document 3: Japanese Laid-Open Patent Publication No. 2008-99503.

Patent Document 4: Japanese Patent No. 3121378.

Patent Document 5: Japanese Laid-Open Patent Publication No. 2001-268900.

However, it is used as a simple configuration of a bidirectional type buck-boost chopper that is capable of charging control from the DC bus to the power storage element and discharging control from the power storage device to the DC bus. In the case of a DC/DC converter of the power storage device, the switching circuit side of the buck-boost chopper circuit is connected to the DC bus, and the choke coil is connected to the power storage element, or is opposite. In the connection relationship, when charging from the DC bus to the power storage element, even if there is sufficient power in the power storage element, there is a case where the charging voltage cannot be charged to a voltage higher than the bus voltage, or in the self-power storage element. When discharging to the DC bus, even if it is possible to discharge from the power storage element, there is a case where only a voltage equal to the bus voltage can be discharged.

In order to solve this problem, for example, two circuits shown in Patent Documents 4 and 5 may be connected in series to control the configuration of a switching circuit. According to this configuration, the power storage element can be charged from the DC bus and discharged from the power storage element to the DC bus line irrespective of the bus voltage. However, the circuit configuration becomes complicated and the control becomes complicated. In addition to this, since power loss occurs in each of the switching circuits of the two circuits, the conversion efficiency of the energy is lowered.

The present invention has been made in view of the foregoing problems, and an object thereof is to obtain a chopper circuit equipped with a circuit that does not require a bidirectional type buck-boost circuit for a power storage device. An AC motor drive device for a power storage device that can improve the energy utilization efficiency by charging and discharging the power storage element irrespective of the bus voltage.

Further, an object of the present invention is to provide, in addition to the object of the foregoing invention, another configuration including a bidirectional type buck-boost circuit for use in a power storage device for preventing an abnormality in occurrence of an electric storage element. The device generates an AC motor drive for the power storage device with a higher impact on the occurrence of damage or breakage.

In order to achieve the object of solving the above problems, the present invention provides an AC motor drive device that converts DC power supplied from a DC bus connected from a DC power source into AC power necessary for driving an AC motor. The power converter is connected in parallel to the DC bus and controls the DC power of the DC bus. The power storage device is provided with: a power storage component, which can store DC power; and a buck-boost bidirectional interceptor circuit. a series circuit of two switching elements and a choke coil having one end connected to the series connection ends of the two switching elements as main constituent elements, and disposed between the DC bus and the power storage element for performing DC from the DC a charging operation of the bus bar to the power storage element and a discharge operation from the power storage element to the DC bus; and a circuit switching element for switching the configuration of the step-up and step-down bidirectional circuit to: a first chopper circuit and a second chopper circuit that connects a positive end of the series circuit to a positive side of the DC bus and a other end of the choke coil to a positive terminal of the power storage element; The second chopper circuit connects the other end of the choke coil to the positive side of the DC bus. The positive terminal of the series circuit is connected to the positive terminal of the power storage element; and the control circuit is configured to compare the voltage of the DC bus to the voltage of the power storage component and before and after the timing of changing the magnitude relationship The switching element is configured to be switched to a circuit corresponding to the first chopper circuit and the second chopper circuit, and the first carrier circuit and the second chopper circuit are operated in a predetermined order to realize the foregoing The charging operation and the aforementioned discharging operation.

According to the present invention, the first and second chopper circuits are used separately Among them, one of the charging operation and the discharging operation is affected by the bus voltage, but focusing on the point of the buck-boost characteristic that complements each other's shortcomings, and the first and second intercepts are used during charging and discharging. Circuit. Thereby, the charge and discharge of the power storage element can be performed irrespective of the bus voltage, and an AC motor drive device equipped with a power storage device capable of improving energy use efficiency can be realized.

Hereinafter, an embodiment of the AC motor driving device of the present invention will be described in detail based on the drawings. Further, the present invention is not limited by the embodiment.

(First Embodiment)

Fig. 1 is a block diagram showing the configuration of an AC motor driving device according to a first embodiment of the present invention. In the first embodiment, the AC motor driving device according to the first embodiment is connected to a plurality of inverters 3, 3, ..., which are supplied with DC power from the DC power source 1 in parallel, and is connected to a DC. The DC bus 2a, 2b between the power source 1 and the inverter 3 is connected in parallel with the inverter 3 in the power storage device 4. AC motors 5, 5, ... are connected to each of the plurality of inverters 3, 3, ....

The plurality of inverters 3, 3, ... generate respective desired AC power from the DC power of the DC bus bars 2a, 2b, and drive the respective AC motors 5, 5, .... Further, in the first drawing, the number of sets of the inverter 3 and the AC motor 5 is shown as a complex array, but there are only one set. In short, since the power storage devices 4 are provided in a group, the number of the inverters 3 and the AC motor 5 is small, and this is not a problem in the present embodiment. The composition of the inverter 3 is quite familiar, so here for the DC power supply 1 and The configuration of the power storage device 4 will be described.

Fig. 2 is a detailed circuit diagram showing a portion of the DC power supply shown in Fig. 1. In the second drawing, the DC power supply 1 shown in Fig. 1 includes a reactor 13, a full-wave rectifying circuit 14, and a smoothing capacitor 15.

The full-wave rectifier circuit 14 is configured by connecting three sets of upper and lower arm switching elements (SW1, SW2) (SW3, SW4) (SW5, SW6) connected in series in parallel. The switching elements SW1 to SW6 are, for example, insulated gate bipolar transistors (IGBTs), but flywheel diodes D1 to D6 are connected in reverse in parallel.

The series connection ends of the three sets of upper and lower arm switching elements (SW1, SW2) (SW3, SW4) (SW5, SW6) connected in series are three-phase AC input terminals. The three-phase AC input terminal is connected to a three-phase AC power supply 11 via a reactor 13 and a transformer 12. In addition, both ends (parallel connection ends) of the upper and lower arm switching elements (SW1, SW2) (SW3, SW4) (SW5, SW6) are DC output terminals (positive output terminal, negative output terminal), and the connection is positive or negative. DC busbars 2a, 2b.

The switching elements SW1 to SW6 of the full-wave rectifying circuit 14 are rectified by switching a three-phase AC voltage with a timing that does not overlap each other. The equalizing capacitor 15 is disposed between the positive and negative DC bus bars 2a, 2b for flattening the rectified voltage of the full-wave rectifier circuit 14 output to the positive and negative DC bus bars 2a, 2b, and forming between the positive and negative DC bus bars 2a, 2b. The predetermined DC voltage (DC power supply).

In addition, the full-wave rectifier circuit 14 is connected from the power storage device 4 The regenerative electric power stored is discharged to the power regeneration mode of the DC bus bars 2a and 2b, and the switching elements SW1 to SW6 are controlled such that the regenerative electric power is regenerated to the AC power supply 11.

Next, Fig. 3 is a block diagram showing the configuration of the power storage device shown in Fig. 1. As shown in FIG. 3, the power storage device 4 includes a power storage element 21, a step-up/down bidirectional interceptor circuit 22, and a control circuit 23.

The power storage element 21 is constituted by a large-capacity electrolytic capacitor or an electric double layer capacitor (EDLC) (see FIG. 4). The buck-boost bidirectional interceptor circuit 22 is a two-way operation capable of charging the power storage element 21 from the DC bus bars 2a, 2b and discharging from the power storage element 21 to the DC bus bars 2a, 2b. In the first embodiment, the "circuit switching element 51" is provided in the step-up/down bidirectional interceptor circuit 22 (see Fig. 5). The control circuit 23 controls the bidirectional buck-boosting operation of the step-up and step-down chopper circuit 22 by a program control executed by a microcomputer. When this operation is performed, in the first embodiment, the control circuit 23 forms control for performing the "circuit switching element 51" provided in the step-up and step-down bidirectional circuit breaker circuit 22.

Fig. 4 is a block diagram showing a configuration example of the power storage element shown in Fig. 3. Fig. 4 shows a case where the power storage element 21 is constituted by an electric double layer capacitor (EDLC). In Fig. 4, the power storage element 21 is an EDLC unit (unit) which is connected in series and in parallel with m × n (m, n is an integer of 1 or more) EDLC modules 31, 31... . EDLC The module 31 is a voltage balance in which a plurality of EDLC cells 32, 32, ... are connected in series, and in order to reduce uneven voltage distribution between the EDLC cells 32, 32, ... Balance resistors 33, 33... are formed.

The power storage element 21 configured as described above has a capacitance of, for example, a large capacity of about one Farad (F). The electrostatic capacity of an EDLC cell 32 is typically greater than 100 F and the maximum voltage is approximately 3 volts (V) or less. Further, since the voltage between the DC bus bars 2a and 2b is usually 300 V or 600 V, the voltage of the power storage element 21 is practically 150 V or more. Further, the power storage element 21 also includes a fuse or a breaker, but is omitted from Fig. 4. Further, the voltage balance resistor 33 may be omitted or may be provided in another balanced manner.

Fig. 5 is a circuit diagram showing a configuration example of a specific configuration of the step-up and step-down chopper circuit shown in Fig. 3. Although various circuit configurations have been known in the buck-boost bidirectional chopper circuit 22, in the present embodiment, for example, as shown in Fig. 5, the simplest circuit configuration is employed.

In Fig. 5, the buck-boost bidirectional chopper circuit 22 is connected in series with two switching elements (e.g., IGBTs) 41a, 41b, and one end connected to the two switching elements 41a, 41b (in the example of the figure) The choke coil 43 of the emitter terminal of the intermediate switching element 41a and the collector terminal of the switching element 41b, and the circuit switching element 51 according to the first embodiment are main components. Composition. Further, flywheel diodes 42a and 42b are connected to the switching elements 41a and 41b in antiparallel.

The negative terminal of one end of the series circuit belonging to the switching elements 41a, 41b (the emitter terminal of the switching element 41b in the illustrated example) and the negative terminal of the power storage element 21 are commonly connected to the DC bus 2b of the negative electrode. The smoothing capacitor 44a is connected between the DC bus bars 2a and 2b. Further, the smoothing capacitor 44b is connected between the positive terminal and the negative terminal of the power storage element 21. In addition, there are cases where the smoothing capacitors 44a and 44b are omitted.

Here, the circuit switching element 51 according to the first embodiment is configured such that the two sets of switching circuits (a, a1, a2) and (b, b1, b2) are operated in conjunction with the driving unit shown in the frame. In one of the switching circuits (a, a1, a2), the switching base a is connected to the positive terminal of the power storage element 21, the switching end a1 is connected to the other end of the choke coil 43, and the switching end a2 is connected to The positive terminal (the collector terminal of the switching element 41a in the illustrated example) belonging to the other end of the series circuit of the switching elements 41a, 41b. Further, in the other switching circuit (b, b1, b2), the switching base b is connected to the DC bus 2a of the positive electrode, the switching terminal b1 is connected to the collector terminal of the switching element 41a, and the switching terminal b2 is connected. At the other end of the choke coil 43.

The control circuit 23 inputs: the voltage of the DC bus 2a, 2b detected by the voltage sensor 45a, the voltage of the power storage element 21 detected by the voltage sensor 45b, and the current sensor 46a. The bus current and the current flowing through the choke coil 43 detected by the current sensor 46b serve as a reference for controlling the two switching elements 41a, 41b and the circuit switching element 51 of the buck-boost bidirectional chopper circuit 22. Signal. In addition, the detection value of the input control circuit 23 is not limited to the above four, and the foregoing is an example, and there are cases where other detection values are input. In addition, there is also a top position from the unillustrated The controller is entered and the situation is entered.

The control circuit 23 generates a gate signal for individually switching the switching elements 41a, 41b based on the detected values, and causes the buck-boost bidirectional chopper circuit 22 to perform regenerative power from the motor 5. The operation of charging the power storage element 21 and the operation of discharging the regenerative electric power stored in the power storage element 21 (power supply regeneration). At this time, the control circuit 23 controls the circuit configuration of the step-up and step-down bidirectional chopper circuit 22 according to the circuit switching element 51 of the first embodiment based on the detected values, and changes the circuit configuration to the first chopper circuit. (Fig. 6) and the second chopper circuit (Fig. 7).

Specifically, in the first switching circuit (Fig. 6), in the circuit switching element 51, the switching base terminal a and the switching terminal a1 are connected to one switching circuit (a, a1, a2) to resist current. The other end of the coil 43 is connected to the positive terminal of the power storage element 21; and the switching base b and the switching end b1 are connected to the other switching circuit (b, b1, b2) to switch the terminal of the element 41a, The configuration of the DC bus 2a connected to the positive electrode.

Further, in the second switching circuit (Fig. 7), in the circuit switching element 51, the switching base terminal a and the switching terminal a2 are connected to one switching circuit (a, a1, a2) to switch the element 41a. The collector terminal is connected to the positive terminal of the power storage element 21; and the switching base b and the switching terminal b2 are connected to the other switching circuit (b, b1, b2), and the other end of the choke coil 43 is connected to The configuration of the DC bus 2a of the positive electrode.

The first chopper circuit shown in Fig. 6 can perform step-down charging from the DC bus bars 2a, 2b to the power storage element 21, and can perform boost discharge from the power storage element 21 to the DC bus bars 2a, 2b. . Conversely, the first The second chopper circuit shown in FIG. 7 can perform step-up charging from the DC bus bars 2a and 2b to the power storage element 21, and can perform step-down discharge from the power storage element 21 to the DC bus bars 2a and 2b.

The first chopper circuit and the second chopper circuit can be generally used as the bidirectional chopper circuit in the power storage device 4. However, since the charging and discharging operation is affected by the bus voltage, the conventional The power storage capacity (storage energy) of the power storage element 21 cannot be fully utilized. In this regard, a brief description will be given with reference to FIGS. 8 and 9. In addition, Fig. 8 is a characteristic diagram for explaining the charge and discharge characteristics of the first chopper circuit shown in Fig. 6. Fig. 9 is a characteristic diagram for explaining the charge and discharge characteristics of the second chopper circuit shown in Fig. 7.

Fig. 8 shows: (1) voltage changes of the DC bus bars 2a, 2b, (2) charging and discharging operations with respect to the power storage element 21 at the (1) point, and (3) display of the DC bus bars 2a, 2b. The voltage difference between the voltage V1 and the voltage V2 of the power storage element 21 (V3 = V2 - V1). Further, the voltage V1 of the DC bus bars 2a and 2b is set to the discharge start voltage 60 belonging to the power regeneration operation threshold.

In Fig. 8 (1), the DC bus voltage V1 is associated with the rising period 61 corresponding to the deceleration period; thereafter, the constant voltage period 62 corresponds to the constant speed period; and thereafter, the falling period 63 corresponds to the acceleration period.

In Fig. 8 (2), charging is started in the power storage element 21 at the initial timing 64 of the DC bus voltage rising period 61. The charging operation is performed until the voltage V2 to the power storage element 21 is equal to the DC bus voltage V1. In Figure 8, it is shown that the DC bus voltage V1 is at a constant voltage. At the timing 65 near the terminal of the period 62, the voltage V2 of the power storage element 21 is equal to the DC bus voltage V1.

In this case, since the DC bus voltage V1 falls from the constant voltage in the timing 66 after the charging end timing 65, a condition of V2 > V1 is formed. As a result, since the natural discharge from the power storage element 21 to the DC bus 2a via the flywheel diode 42a occurs, the voltage V2 of the power storage element 21 also decreases from the maximum charging voltage. At this time, the control circuit 23 can recognize the current flowing through the choke coil 43 as a notification from the current sensor 46b, but cannot cut the current. As a result, the current naturally discharged to the DC bus 2a via the flywheel diode 42a continues to flow until the power storage element 21 and the DC bus bars 2a, 2b reach the same voltage timing 67.

Furthermore, the DC bus voltage V1 is at a timing 67 lower than the discharge start voltage 60, and power regeneration is started. The voltage of the power storage element 21 at the timing 67 of the power regeneration is lower than the voltage from the maximum charging voltage at the timing 66 up to the voltage 68, which is about 60% of the maximum charging voltage in the illustrated example. Voltage 68 is equivalent to energy loss. In other words, when the first chopper circuit is used, since the voltage at the start of discharge of the power storage element 21 is lower than the maximum charging voltage, the discharge current flowing through the choke coil 43 is increased because of the lower voltage. The increase is the loss of energy, and it is the main reason for reducing the efficiency of energy storage.

Next, in Fig. 9, the relationship between the buck-boost is reversed, but similarly to Fig. 8, (1) voltage changes of the DC bus bars 2a and 2b, and (2) power storage with respect to the (1) point. Charge and discharge operation of element 21, (3) and A voltage difference (V3 = V1 - V2) showing the relationship between the voltage V1 of the DC bus bars 2a, 2b and the voltage V2 of the power storage element 21 is shown. Further, the voltage V1 of the DC bus bars 2a and 2b is set to a charge start voltage 70 and a discharge start voltage 71 belonging to the power regeneration operation threshold. The charge start voltage 70 is the > discharge start voltage 71.

In Fig. 9 (1), the DC bus voltage is such that the falling period 71 corresponds to the acceleration period; thereafter, the constant voltage period 73 corresponds to the constant speed period; and thereafter the rising period 74 corresponds to the deceleration period.

As can be understood from the configuration of Fig. 7, when the voltage V1 of the DC bus bars 2a, 2b is higher than the voltage V2 of the power storage element 21, the power storage element 21 is charged (naturally charged) via the flywheel diode 42a. The timing 75 in Fig. 9 performs natural charging as in the foregoing manner. As a result, when the bus voltage V1 falls and is lower than the discharge start voltage 71 at the timing 76, the discharge starts. The discharge operation is performed until the voltage V2 to the power storage element 21 and the DC bus voltage V1 become equal. In the ninth diagram, the DC bus voltage V1 at the timing 77 near the terminal belonging to the constant voltage period 73 indicates that the voltage V2 of the power storage element 21 is equal to the DC bus voltage V1.

In this case, since the DC bus voltage V1 rises from the constant voltage in the timing 78 after the discharge completion timing 77, a state of V1 > V2 is formed. As a result, since the natural discharge from the DC bus 2a to the power storage element 21 via the flywheel diode 42a occurs, the voltage V2 of the power storage element 21 also rises. Thus, the DC bus voltage V1 begins its original charging at a timing 79 that exceeds the charge start voltage 70. From The period from the timing 77 to the timing 79 is a period in which the voltage difference V3 is zero. In other words, when the second chopper circuit is used, since the discharge from the power storage element 21 can only be performed to a voltage equal to the bus voltage, the utilization efficiency of the stored energy source that can be utilized by the power source regeneration is not good.

Here, the review is made from the viewpoint of improving the energy use efficiency at the time of power regeneration. Here, when Va is the pre-discharge voltage of the power storage element 21, and Vb is the post-discharge voltage, the usable power P is P=(Va ^{2 -} Vb ² )/2. In order to improve the energy utilization efficiency of the electric storage in the power storage element 21, it is necessary to control so as to set the pre-discharge voltage Va as high as possible, and to set the post-discharge voltage Vb as low as possible.

As shown in FIGS. 8 and 9, the first and second chopper circuits are used alone, and one of the charging operation and the discharging operation is affected by the bus voltage, so that the power storage voltage cannot be satisfied. The way to control is to have the buck-boost characteristics that complement each other's shortcomings. Therefore, in the first embodiment, the circuit switching element 51 is provided in the buck-boost bidirectional interceptor circuit 22, and the charge and discharge control circuit shown in FIG. 10 is provided in the control circuit 23, and the first chopper circuit is The second chopper circuit is used in combination at the time of charging and discharging as described below.

In Fig. 10, the charge and discharge control circuit can be constituted by a comparator 81, logic "No" circuits 82, 83, 84, logic "AND" circuits 85 to 90, and logic OR circuits 91, 92. . The comparator 81 is connected to the non-inverting input terminal (+) to input the voltage V2 of the power storage element 21; the inverting input terminal (-) is input to the DC bus voltage V1, and the output is compared. The circuit switching request signal of the operation result is S11.

In this configuration, the output of the comparator 81 (circuit switching request signal S11) forms a low level (hereinafter referred to as "L" level) when V1 > V2; and a high level when V1 < V2 ( The following is described as ""H" level"). The circuit switching request signal S11 is input to the circuit switching element 51 and is input to one of the logical AND circuits 87 and 88, and is input to one of the logical AND circuits 89 and 90 by the logic NO circuit 82.

Further, in the comparison operation of the comparator 81, when switching from V1 > V2 to V1 < V2 and when switching in the reverse direction, the output level may be switched immediately at the timing of V1 = V2, but it is also possible It is assumed that a fixed dead zone is set, and switching of the circuit is not performed when the state of V1 = V2 occurs only for a short time, and switching is performed at a fixed delay time. Further, when switching between fixed delay times, the time widths t1 and t2 may be different when switching from V1>V2 to V1<V2 and when switching in the reverse direction (see FIG. 11 and FIG. 12).

The circuit switching element 51 forms a first chopper circuit (FIG. 6) when the circuit switching request signal S11=“L” level is in the first embodiment; and the circuit switching request signal S11=“H” level A second chopper circuit is formed (Fig. 7).

The charging command signal S1 is generated when the DC bus voltage V1 exceeds a predetermined charging start voltage. Further, the discharge command signal S2 is generated when the DC bus voltage V1 is lower than a predetermined discharge start voltage.

The input of one of the logical AND circuits 85 is the charge command signal S1, and the other input is the discharge command signal S2 that passes through the logic "NO" circuit 84. The output of the logical AND circuit 85 becomes a logical "and" The input to the other of the roads 87, 89.

The input of one of the logical AND circuits 86 is the discharge command signal S2, and the other input is the charge command signal S1 that passes through the logic "NO" circuit 83. The output of the logical AND circuit 86 is the input to the other of the logical AND circuits 88,90.

The logical OR circuit 91 inputs the outputs of the logical AND circuits 87, 88 and outputs the boosted chopper circuit operation signal S21. The "boost chopper circuit" described here is the first chopper circuit at the time of discharge and the second chopper circuit at the time of charging. In addition, a logical OR circuit 92 inputs the outputs of the logical AND circuits 89, 90 and outputs a buck chopper circuit operation signal S22. The "buck chopper circuit" described here is the second chopper circuit at the time of discharge and the first chopper circuit at the time of charging. The driving signals are generated in such a manner that the switching elements 41a and 41b can complement each other in accordance with the outputs of the logical OR circuits 91 and 92, and are applied to the corresponding gate terminals of the switching elements 41a and 41b. .

Here, in the first embodiment, the control circuit 23 is configured to: (1) control the charging of the power storage element 21 to a predetermined initial charging voltage when the power of the device is activated, and (2) thereafter. When the AC motor 5 is driven, the charge/discharge between the power storage element 21 and the DC bus bars 2a and 2b is controlled, and (3) when the power supply end device is turned off, the power storage element 21 is turned to the DC bus. Control of discharge of 2a, 2b to a predetermined discharge limit voltage. The measure of (1) is a measure of the ability to fully utilize the power storage element 21. (3) The measures are safety measures when the power of the device is turned off and the power storage element 21 is replaced.

Referring to Fig. 10, the charge/discharge control operation of (1), (2), and (3) will be described, and (1) and (3) will be described separately from (2), and (1) and (3) may be used. ) is related or not related to (2). Here, it is assumed that (2) and (1) and (3) have no operational correlation.

(1) Charging control at power-on

When the power is turned on, the charging command signal S1 is at the "H" level; the discharging command signal S2 is at the "L" level. Therefore, the output of the logical AND circuit 85 is at the "H" level, and the output of the logical AND circuit 86 is at the "L" level. Since the DC bus voltage V1 is higher than the voltage V2 of the power storage element 21, the circuit switching request signal S11 output by the comparator 81 is at the "L" level. The buck-boost bi-directional chopper circuit 22 forms a first chopper circuit (Fig. 6). The output of the logical AND circuit 89 changes to the "H" level, and the logic OR circuit 92 outputs the buck chopper circuit operation signal S22. The first bus detector circuit (Fig. 6) charges the power storage element 21 while stepping down the DC bus voltage V1.

When charging to the power storage element 21 is performed and the voltage V2 of the power storage element 21 is equal to the DC bus voltage V1, the comparator 81 switches the circuit switching request signal S11 from the "L" level to the "H" level. As a result, the step-up and step-down chopper circuit 22 is switched to the second chopper circuit (Fig. 7). The output of the logical AND circuit 87 becomes "H" level, and the logic OR circuit 91 outputs the boosted chopper circuit operation signal S21. By the second chopper circuit (Fig. 7), the DC bus voltage V1 is boosted, and charging of the power storage element 21 is continued until the voltage V2 of the power storage element 21 becomes equal to the initial charging voltage. At the 2nd In the chopper circuit (Fig. 7), when the voltage V2 of the power storage element 21 is higher than the DC bus voltage V1, the switching elements 41a and 41b stop operating, but since the power storage element 21 is not formed, the DC bus 2a is not formed. Since the discharge path of 2b is such that the voltage V2 of the power storage element 21 is maintained at an initial charging voltage higher than the DC bus voltage V1.

(2 of 1) Charging control during AC motor drive operation

Since the DC bus voltage V1 that changes according to the operating state of the AC motor exceeds the charging start voltage, when the charging command signal S1 becomes the "H" level and the discharging command signal S2 is at the "L" level, the comparator 81 will When the circuit switching request signal S11 is set to the "L" level, the step-up and step-down bidirectional interceptor circuit 22 forms a first chopper circuit (Fig. 6). The output of the logical AND circuit 89 changes to the "H" level, and the logic OR circuit 92 outputs the buck chopper circuit operation signal S22. The first bus detector circuit (Fig. 6) charges the power storage element 21 while stepping down the DC bus voltage V1.

When charging to the power storage element 21 is performed and the voltage V2 of the power storage element 21 becomes equal to the DC bus voltage V1, the comparator 81 switches the circuit switching request signal S11 from the "L" level to the "H" level. In this way, the step-up and step-down chopper circuit 22 is switched to the second chopper circuit (Fig. 7). The output of the logical AND circuit 87 becomes "H" level, and the logic OR circuit 91 outputs the boosted chopper circuit operation signal S21. The second chopper circuit (Fig. 7) continuously charges the power storage element 21 while boosting the DC bus voltage V1. In the second chopper circuit (Fig. 7), the voltage V2 at the power storage element 21 is higher than the DC mother In the state of the line voltage V1, the switching elements 41a and 41b are stopped. However, since the discharge path from the power storage element 21 to the DC bus bars 2a and 2b is not formed, the voltage V2 of the power storage element 21 is maintained higher than the DC bus voltage. The voltage of V1. In other words, the discharge start voltage can be maintained at a maximum charging voltage higher than the DC bus voltage V1. Therefore, since the discharge current flowing through the choke coil 43 at the time of discharge is reduced, power loss can be reduced.

(2 of 2) Discharge control during AC motor drive operation

In the state where the comparator 81 sets the circuit switching request signal S11 to the "H" level and the step-up and step-down bidirectional wave cutter circuit 22 forms the second chopper circuit (Fig. 7), the operating state of the corresponding AC motor The changed DC bus voltage V1 is lower than the discharge start voltage. Therefore, when the discharge command signal S2 becomes the "H" level and the charge command signal S1 is at the "L" level, the output of the logical AND circuit 88 becomes The "H" level is output, and the logic OR circuit 91 outputs a boost chopper circuit operation signal S21. The second chopper circuit (Fig. 7) discharges the DC busbars 2a and 2b while stepping down the voltage V2 of the power storage element 21.

When the discharge to the DC bus bars 2a, 2b is performed, and the voltage V2 of the power storage element 21 is equal to the DC bus voltage V1, the comparator 81 switches the circuit switching request signal S11 from the "H" level to the "L" level. . As a result, the step-up and step-down chopper circuit 22 is switched to the first chopper circuit (Fig. 6). The output of the logical AND circuit 90 changes to the "H" level, and the logic OR circuit 92 outputs the buck chopper circuit operation signal S22. The first chopper circuit (Fig. 6) continuously discharges the voltage V2 of the power storage element 21 to the DC bus bars 2a and 2b. In other words Since the voltage V2 of the power storage element 21 is discharged so as to be equal to or lower than the voltage V1 of the DC bus bars 2a and 2b, the utilization efficiency of the power storage energy of the power storage element 21 can be improved.

(3) Discharge control at the end of the device operation

When the device is powered off and the device is terminated, the discharge command signal S2 becomes "H" level, and the charge command signal S1 forms an "L" level. The comparator 81 sets the circuit switching request signal S11 to the "H" level, and when the step-up/down bidirectional chopper circuit 22 is formed as the second chopper circuit (Fig. 7), the logical AND circuit 88 The output becomes the "H" level, and the logic "OR" circuit 91 outputs the boosted chopper circuit operation signal S21. The second chopper circuit (Fig. 7) discharges the voltage V2 of the power storage element 21 to the DC bus bars 2a and 2b.

When charging to the DC bus bars 2a, 2b is performed and the voltage V2 of the power storage element 21 is equal to the DC bus voltage V1, the comparator 81 switches the circuit switching request signal S11 from the "H" level to the "L" level. As a result, the step-up and step-down chopper circuit 22 is switched to the first chopper circuit (Fig. 6). The output of the logical AND circuit 90 changes to the "H" level, and the logic OR circuit 92 outputs the buck chopper circuit operation signal S22. By the first chopper circuit (Fig. 6), the voltage V2 of the power storage element 21 is discharged to the DC bus bars 2a and 2b while being stepped down to the discharge limit voltage equal to or lower than the DC bus voltage V1.

Fig. 11 is a waveform diagram showing the main part of the charging operation according to the first embodiment. Fig. 12 is a waveform diagram showing the main part of the discharge operation according to the first embodiment. Figure 11 and Figure 12 show the integration The diagram of the charging operation and the discharging operation described above.

As shown in Fig. 11, the voltage V2 of the power storage element 21 can be increased beyond the voltage V1 of the DC bus bars 2a, 2b without depending on the voltage V1 of the DC bus bars 2a, 2b, and can be charged to the power storage element 21 for charging. The maximum voltage (initial charging voltage) is up.

Further, as shown in Fig. 12, since the voltage V2 of the power storage element 21 at the start of discharge is higher than the voltage V1 of the DC bus 2a, 2b, the reusable energy from the power storage element 21 can be increased. the amount. Further, the discharge current flowing through the choke coil 43 is lowered, and power loss can be reduced. Further, regardless of the voltage V1 of the DC bus bars 2a and 2b, it is possible to discharge to the lowest dischargeable voltage (discharge limit voltage) of the power storage element 21 which is lower than the voltage V1 of the DC bus bars 2a and 2b.

As described above, according to the first embodiment, a buck-boost coil that can be configured to connect a series circuit of two switching elements and one end of the two switching elements to the series connection end of the two switching elements is provided as a main component The circuit is switched such that the positive terminal of the series circuit of the two switching elements is connected to the DC bus and the other end of the choke coil is connected to the first chopper circuit of the power storage element to the positive terminal, and the series connection of the two switching elements The positive terminal of the circuit is connected to the positive terminal of the power storage element, and the other end of the choke coil is connected to the circuit switching component of the second chopper circuit of the DC bus; during charging and discharging, it is set to be adjacent to the DC bus voltage Since the first chopper circuit and the second chopper circuit are switched in sequence with the magnitude of the voltage of the power storage element, the power storage element can be charged to exceed the DC bus during charging without being affected by the DC bus voltage. High voltage Until the maximum voltage that can be charged, it can be discharged from the power storage element to a low voltage (the lowest voltage possible for discharge) from the DC bus voltage.

Therefore, at the time of charging, the maximum energy that can be stored in the power storage element can be stored, and the energy stored in the power storage element can be utilized to the maximum extent during the discharge, so that power storage capable of improving energy utilization efficiency can be realized. AC motor drive for the unit.

(Second embodiment)

Fig. 13 is a circuit diagram showing a configuration example of a power storage device which can cope with an abnormality occurring as a second embodiment of the present invention. Further, in Fig. 13, the same or equivalent constituent elements as those shown in Fig. 5 (first embodiment) are denoted by the same reference numerals. Here, the key points related to the second embodiment will be described.

In Fig. 13, in the configuration of the power storage device 4 according to the second embodiment shown in Fig. 5 (first embodiment), two circuit switching elements 52a and 52b are provided instead of the circuit switching element 51. Further, an abnormal signal is input to the control circuit 23 from inside the device or outside the device.

The abnormality signal input from the inside of the apparatus is displayed on the DC power supply 1 or the inverter 3 to generate a failure to lower the voltage of the DC bus bars 2a, 2b, and to short-circuit the DC bus bars 2a, 2b. The abnormal signal input from the outside of the device is input when it is necessary to stop the device.

The circuit switching elements 52a and 52b are individually independent, but are provided with switching circuits (a, a11, a12) that share the switching base end a connected to the positive terminal of the power storage element 21. (a, a21, a22) , sharing and positive The switching circuit (b, b11, b12) (b, b21, b22) of the switching base b is connected to the DC bus 2a.

In the switching circuit (a, a11, a12) (b, b11, b12) of the circuit switching element 52a, the switching end a21 is connected to the other end of the choke coil 43, and the switching terminal b12 is connected to the collector terminal 41a. The subphases are connected, but the switching terminals a11, b11 are not connected anywhere. Therefore, the circuit switching element 52a can perform an operation of connecting the switching base end a to the switching terminal a12 and switching the base end b to the switching terminal b12 to form the first chopper circuit, and the switching base end a is connected to the switching end a11. And the switching base end b is connected to the switching terminal b11 to open and cut between the DC bus bars 2a and 2b and the buck-boost bidirectional interceptor circuit 22 and between the buck-boost bidirectional chopper circuit 22 and the power storage element 21. action.

In the switching circuit (a, a21, a22) (b, b21, b22) of the circuit switching element 52b, the switching end a22 is connected to the collector terminal of the switching element 41a, and the switching terminal b22 is connected to the anti-current coil 43. One end is connected, but the switching ends a21, b22 are not connected anywhere. Therefore, the circuit switching element 5ba can be configured such that the switching base end a is connected to the switching end a22 and the switching base end b is connected to the switching end b22 to form a second chopper circuit, and the switching base end a is connected to the switching end a21. The switching base end b is connected to the switching terminal b21 to open and close the DC bus bars 2a and 2b and the buck-boost bidirectional interceptor circuit 22 and between the buck-boost bidirectional chopper circuit 22 and the power storage element 21. .

The control circuit 23 is in a sound and normal operating state of the device, and the circuit switching elements 52a, 52b are correspondingly charged or discharged. The predetermined sequence is outputted to the circuit switching request signal S11 described in the first embodiment. Further, the control circuit 23 is in the normal operation state described above, and when the abnormal signal is input, the circuit switching element that performs circuit switching among the circuit switching elements 52a and 52b, the output circuit cutoff request signal S12, and the direct current The bus bars 2a, 2b and the buck-boost bidirectional interceptor circuit 22 and the buck-boost bidirectional interceptor circuit 22 are opened and disconnected from the power storage element 21.

Thereby, since the energy stored in the power storage element 21 can be maintained without being reduced, the energy stored in the power storage element 21 can be utilized to the maximum extent.

Further, for example, when the step-up/down bidirectional interceptor circuit 22 operates to form the first chopper circuit, when a certain abnormality occurs in the power supply device 1 or the inverter 3, and the voltages of the DC power supply bus bars 2a and 2b are lowered, The discharge to the DC bus 2a side via the flywheel diode 42a occurs. This discharge is a natural discharge that the control circuit 23 cannot control. Since the discharge current at this time is a large current, if it is ignored, the device existing in the current path may be damaged, or the adverse effect such as the expansion of the power supply device 1 or the inverter 3 may be affected to the peripheral circuit. But this situation can be prevented.

Therefore, in Fig. 13, there is shown a situation in which the DC bus bars 2a, 2b and the step-up and step-down bidirectional wave cutter circuit 22 are opened and cut between the step-up and step-down bidirectional interceptor circuit 22 and the power storage element 21. The configuration may be such that the disconnection is performed when the abnormality occurs, but at least the openable cut-off bidirectional interceptor circuit 22 and the power storage element 21 may be formed.

According to the second embodiment, since the power storage element 21 is included The other devices of the buck-boost bi-directional chopper circuit 22 are disconnected, so that the damage of the power storage element 21 to other devices may be prevented from being damaged or damaged, and the communication of the power storage device equipped with higher security may be realized. Motor drive unit. In addition to this, an AC motor drive device equipped with a power storage device that can utilize the energy stored in the power storage element 21 to the maximum extent can be realized.

(Third embodiment example)

Fig. 14 is a circuit diagram showing another configuration example of the power storage device which can correspond to the occurrence of an abnormality, and is a third embodiment of the present invention. Further, in Fig. 14, the same or equivalent constituent elements as those shown in Fig. 13 (second embodiment) are denoted by the same reference numerals. Here, the key points of the third embodiment will be described.

In Fig. 14, the power storage device 4 according to the third embodiment is in the configuration shown in Fig. 13 (second embodiment), and the control circuit 23 is input from the inside of the device or the outside of the device. The abnormal signal described in the embodiment; however, a circuit switching element 53 is provided instead of the circuit switching elements 52a, 52b.

The circuit switching element 53 is configured to operate two sets of switching circuits (a, a1, a2, a3) and (b, b1, b2, b3) that surround the driving unit shown in the frame. In one of the switching circuits (a, a1, a2, a3), the switching base a is connected to the positive terminal of the power storage element 21, and the switching end a1 is connected to the other end of the choke coil 43, the switching end a2 Not connected to any place, the switching end a3 is connected to the collector terminal of the switching element 41a. In addition, in the other switching circuit (b, b1, b2, b3), switching the base b and the positive electrode The DC bus 2a is connected, the switching terminal b1 is connected to the collector terminal of the switching element 41a, the switching terminal b2 is not connected to any of the switching terminals b2, and the switching terminal b3 is connected to the other end of the choke coil 43.

Therefore, the circuit switching element 53 can be configured such that the switching base end a is connected to the switching end a1 and the switching base end b is connected to the switching end b1 to form a first chopper circuit, and the switching base end a is connected to the switching end a3. The switching base terminal b is connected to the switching terminal b3 to form a second chopper circuit, the switching base end a is connected to the switching terminal a2, and the switching base end b is connected to the switching terminal b2 to perform the DC bus bars 2a, 2b and the power storage element. The opening cut action between 21s.

The control circuit 23 outputs the circuit switching request signal S11 described in the first embodiment to the circuit switching element 53 in a sound and normal operating state of the device. Further, the control circuit 23 is in the normal operation state described above, and when the abnormal signal is input, the circuit switching element 53 outputs the circuit cut request signal S12, and the DC bus 2a, 2b is connected to the power storage element 21. Open cut.

Similarly to the second embodiment, in Fig. 14, there is shown that between the DC bus bars 2a, 2b and the step-up and step-down bidirectional cutter circuit 22, between the buck-boost bidirectional chopper circuit 22 and the power storage element 21 In the case of the opening and closing, the opening and closing are performed when the abnormality occurs, but at least the switching between the step-up and step-down bidirectional interceptor circuit 22 and the power storage element 21 may be opened.

Therefore, in the third embodiment, the same as the second embodiment, since the power storage element 21 can be from the buck-boost bidirectional interceptor circuit 22 Since the other devices are separated, it is possible to prevent the occurrence of breakage of damage to other devices when the power storage element 21 is connected, and to realize an AC motor drive device equipped with a higher-safety power storage device. In addition to this, an AC motor drive device equipped with a power storage device that can utilize the energy stored in the power storage element 21 to the maximum extent can be realized in the same manner as the second embodiment.

(industrial availability)

As described above, the AC motor driving device of the present invention does not require a switching circuit for setting a two-circuit type of the bidirectional type buck-boost chopper circuit used in the power storage device, and can perform power storage irrespective of the bus voltage. The charging and discharging of components is advantageous as an AC motor driving device equipped with a power storage device capable of improving energy utilization efficiency.

1‧‧‧DC power supply

2a, 2b‧‧‧ DC bus

3‧‧‧Reflux

4‧‧‧Power storage device

5‧‧‧AC motor

11‧‧‧Three-phase AC power supply

12‧‧‧Transformers

13‧‧‧Reactor

15, 44a, 44b‧‧‧ Straddle capacitor

21‧‧‧Power storage components

22‧‧‧Boosting and lowering bidirectional chopper circuit

23‧‧‧Control circuit

31‧‧‧EDLC (Electrical Double Layer Capacitor) Module

32‧‧‧EDLC

33‧‧‧Voltage balance resistor

41a, 41b, SW1 to SW6‧‧‧ switching components

42a, 42b, D1 to D6‧‧‧ flywheel diodes

43‧‧‧Current coil

45a, 45b‧‧‧ voltage sensor

46a, 46b‧‧‧ current sensor

51, 52a, 52b, 53‧‧‧ circuit switching components

81‧‧‧ comparator

82 to 84‧‧‧Logical "No" circuit

85 to 90 ‧ ‧ logical "and" circuit

91, 92‧‧‧Logical OR circuit

A1, a2, b1, b2‧‧‧ switch end

S11‧‧‧ circuit switching request signal

Fig. 1 is a block diagram showing the configuration of an AC motor driving device according to a first embodiment of the present invention.

Fig. 2 is a detailed circuit diagram showing a portion of the DC power supply shown in Fig. 1.

Fig. 3 is a block diagram showing the configuration of the power storage device shown in Fig. 1.

Fig. 4 is a block diagram showing a configuration example of the power storage element shown in Fig. 3.

Fig. 5 is a circuit diagram showing a configuration example of a specific configuration of the step-up and step-down chopper circuit shown in Fig. 3.

Figure 6 is a diagram showing the realization of the circuit switching element shown in Figure 5 1 circuit diagram of the chopper circuit.

Fig. 7 is a circuit diagram showing a second chopper circuit which realizes the circuit switching element shown in Fig. 5.

Fig. 8 is a characteristic diagram for explaining the charge and discharge characteristics of the first chopper circuit shown in Fig. 6.

Fig. 9 is a characteristic diagram for explaining the charge and discharge characteristics of the second chopper circuit shown in Fig. 7.

Fig. 10 is a circuit diagram showing an example of a charge and discharge control circuit provided in the control circuit shown in Fig. 3.

Fig. 11 is a waveform diagram showing the main part of the charging operation according to the first embodiment.

Fig. 12 is a waveform diagram showing the main part of the discharge operation according to the first embodiment.

Fig. 13 is a circuit diagram showing an example of a configuration of a power storage device which can correspond to the occurrence of an abnormality as a second embodiment of the present invention.

Fig. 14 is a circuit diagram showing another configuration example of the power storage device which can correspond to the occurrence of an abnormality as a third embodiment of the present invention.

2a, 2b‧‧‧ DC bus

4‧‧‧Power storage device

21‧‧‧Power storage components

22‧‧‧Boosting and lowering bidirectional chopper circuit

23‧‧‧Control circuit

41a, 41b‧‧‧ Switching components

42a, 42b‧‧‧ flywheel diode

43‧‧‧Current coil

44a, 44b‧‧‧ Straddle capacitor

45a, 45b‧‧‧ voltage sensor

46a, 46b‧‧‧ current sensor

51‧‧‧Circuit switching components

A1, a2, b1, b2‧‧‧ switch end

S11‧‧‧ circuit switching request signal

Claims (8)

An AC motor driving device is provided with a inverter that converts DC power supplied from a DC bus connected to a DC power source into AC power necessary for driving an AC motor, and is connected in parallel to the DC bus, and controls the DC A power storage device for a DC power of a bus bar, the power storage device comprising: a power storage element capable of storing DC power; a buck-boost bidirectional chopper circuit, a series circuit of two switching elements, and one end and the two switching elements a choke coil connected to the series connection end as a main component, and disposed between the DC bus and the power storage element for performing a charging operation from the DC bus to the power storage element and from the power storage element a discharge operation to the DC bus; the circuit switching element is configured to switch the configuration of the buck-boost bidirectional chopper circuit into: a first chopper circuit and a second chopper circuit; the first chopper circuit Connecting the positive terminal of the series circuit to the positive electrode side of the DC bus and the anti-current coil The other end is connected to the positive terminal of the power storage element; the second chopper circuit connects the other end of the choke coil to the positive side of the DC bus and connects the positive end of the series circuit to the power storage element. a positive terminal; and a control circuit for switching the circuit switching element to correspond to the first chopper circuit before and after comparing the voltage of the DC bus to the voltage of the power storage element and switching the magnitude relationship The first chopper circuit and the second chopper circuit are operated in a predetermined order in accordance with a circuit of the second chopper circuit to realize the charging operation and the discharging operation, respectively. The AC motor drive device according to claim 1, wherein the control circuit compares a voltage between the DC bus and a voltage of the power storage element during a driving operation of the AC motor, and is in the DC bus. When the voltage is higher than the voltage of the power storage element to generate a charging command, the circuit switching element is configured to constitute the first chopper circuit, and the operation of charging the power storage element while reducing the voltage of the DC bus is performed; When the voltage of the power storage element rises and is in the vicinity of the timing of the magnitude of the voltage change of the DC bus, the circuit switching element is configured to constitute the second chopper circuit, and while raising the voltage of the DC bus. The action of charging the aforementioned power storage element. The AC motor drive device according to claim 2, wherein the control circuit is configured to cause the second switching circuit to form the second chopper circuit, and if a discharge command is generated, the second block of the configuration is The wave circuit performs an operation of discharging the DC bus while reducing a voltage of the power storage element, and causes the circuit switching element when a voltage of the power storage element decreases and a timing relationship with a voltage of the DC bus is changed Forming the first chopper circuit to increase the power of the power storage element Pressing, the action of discharging the DC bus on the side. The AC motor driving device according to any one of claims 1 to 3, wherein the control circuit compares a voltage of the DC bus and the power when a charging command is generated when the device power is turned on. The voltage of the storage element is such that when the voltage of the DC bus is higher than the voltage of the power storage element, the circuit switching element forms the first chopper circuit, and while reducing the voltage of the DC bus, The operation of charging the power storage element; when the voltage of the power storage element rises and is in the vicinity of the timing of the voltage change relationship of the DC bus, the circuit switching element is configured to constitute the first chopper circuit, and the foregoing The voltage of the DC bus is charged to the power storage element until the voltage of the power storage element exceeds the voltage of the DC bus and reaches a predetermined initial charging voltage. The AC motor driving device according to any one of the preceding claims, wherein the control circuit causes the circuit switching element to be generated when a discharge command is generated when the operation of the power of the power off device is completed. The second chopper circuit is configured to perform an operation of discharging the DC bus while reducing the voltage of the power storage element, and a timing at which the voltage of the power storage element decreases and the voltage of the DC bus is reversed. In the vicinity, the circuit switching element is configured to constitute the first chopper circuit, and the electric power of the power storage element is raised The operation of discharging the DC bus is performed until the voltage of the power storage element is lower than the voltage of the DC bus to the discharge limit voltage. The AC motor drive device according to claim 1, wherein the circuit switching element has at least a configuration in which a connection between a positive terminal of the power storage element and the step-up/down bidirectional chopper circuit is opened. The AC motor drive device according to claim 6, wherein the control circuit is configured to input an abnormal signal from the inside or the outside of the device when the circuit switching element constitutes the first chopper circuit. And causing the circuit switching element to open the connection between the positive terminal of the power storage element and the other end of the choke coil. The AC motor driving device according to claim 6, wherein the control circuit is configured to input an abnormal signal from the inside or the outside of the device when the circuit switching element constitutes the second chopper circuit. And causing the circuit switching element to open the connection between the positive terminal of the power storage element and the positive terminal of the series circuit.